This is one of our biggest pain points, to be honest. Lots of unexpected things.
We currently can’t easily test viewers using bits easily. There are some issues:
Products are not charged when they are in development mode. Why not just not charge it when it’s on a hosted test, and remove the development mode? We can not test it anymore once the app has gone live, or we need to make some test products and live products, which quite frankly is a bit annoying.
useSetLoopback should be removed IMO, it’s confusing and can be easily forgotten. The solution above would make that flag redundant anyway.